1. Field of the Invention
The present invention relates to a navigation apparatus that displays, for a user, guidance information such as routes and a destination, and a data processing method and computer program used therewith.
More specifically, the present invention relates to a navigation apparatus in which, in a navigation system using three-dimensional graphic data, by executing data processing based on a change in terrain altitude, various types of processing, such as displaying of data such as route information and positional information of a vehicle having the navigation apparatus and setting of a camera position, can be executed as processing matching three-dimensional information. The present invention also relates to a data processing method and computer program used therewith.
2. Description of the Related Art
In a navigation system, relatively broad map information is stored beforehand. Based on present position information obtained through the global positioning system (GPS) or from another position detecting device, a corresponding piece of the map information is read and displayed as guidance information to a user.
Many navigation systems have been developed for vehicles and are in use in car-mounted form. In this case, guidance information that is displayed on the screen depending on the momentarily changing present position is sequentially updated. In addition, in response to a destination (or other driving information) which is input from the user (driver), the navigation systems display map information in accordance with a route to the destination.
Moreover, recently, a system is widely used in which, by mixing three-dimensional computer graphics technology with a navigation system, the three-dimensional images of structures such as buildings and roads are rendered and allocated at corresponding positions on the map, and guidance information is displayed as a three-dimensional map.
In another proposed system, information of a route to a destination is displayed in animated form on three-dimensional image data, and a vehicle symbol indicating positional information of a vehicle using the system is displayed as a marker.
In another proposed system, the display form of a three-dimensional image data displayed on the display is set at a viewpoint position of a driver, or a mode can be set in which the image data can be displayed as data of an image viewed from a high position called a “bird's eye view” and in which the position of a camera capturing three-dimensional image data, that is, a camera viewpoint, can be changed. Examples of the related art disclosing technology for changing the camera viewpoint position include, for example, Japanese Unexamined Patent Application Publication No. 2002-24862.
In navigation systems of the related art using the three-dimensional graphics technology, two-dimensional data is used as basic map data itself, and, in most cases, three-dimensional data is used as a graphical representation such as a building or the like displayed on two-dimensional map data.
Positional information of the vehicle using this system is acquired by using externally input positional information such as GPS information. The vehicle symbol on the three-dimensional image data is displayed, in animated form, on the display based on the acquired information, and information of a route starting from the vehicle symbol to a destination is also displayed. In navigation systems of the related art, route information and display data of the vehicle symbol are generated based on two-dimensional data, and this data is drawn together with three-dimensional graphic display data of buildings, etc.
When three-dimensional data is used to display a building, etc., and route information and vehicle symbol generated based on two-dimensional data are displayed on the three-dimensional data, a phenomenon occurs in which the route information or the positional information of the vehicle sinks into the ground or in which the route information or the positional information of the vehicle is disposed in the air at a distance from the ground. Accordingly, the phenomenon causes a situation in which the above information, which is displayed on the display, completely differs from its actual state. This also applies to setting of a camera position. If a camera is set without considering altitude information, a phenomenon occurs in which the camera position sinks into the road or in which the camera position is set at an extremely high position. This phenomenon causes a situation in which the information displayed for the user is inappropriate.